A Rhode Island federal court Wednesday told Microsoft to pay $388 million in damages to Uniloc, a Singapore-based company, for infringing on its 1993 piracy-preventing software registration patent.

And since the Rhode Island jury found Microsoft's infringement willful, the award could be trebled.

Microsoft's having none of it and says it's going to appeal, claiming the Uniloc patent is invalid because the solution is obvious and that it does things differently anyway.

Microsoft initially won a summary judgment in its favor in the case on the theory that its encryption approach is different but that decision was overturned by an appeals court that was told an expert witness had a conflict of interest.

Bloomberg figures the patent award is the fifth-largest in US history and that four of the six largest patent awards have been against Microsoft. The single biggest, the $1.52 billion won by Alcatel-Lucent against Microsoft a couple of years ago, was overturned.

Uniloc, which had asked the jury for upwards of $558 million, filed suit in late 2003 naming XP and Office as treading on its IP. It claimed Microsoft reverse-engineered the widgetry despite a promise not to after seeing it back in the early 90s. It was intended to prevent people from installing software on more than one machine.

The lock was used in a lot of "try and buy" software distributed in magazines and new computers in the 90s under a deal with IBM. The company's US subsidiary was set up in 2003 to license its technology.